The present invention relates to fire resistant welt or beading cords used in upholstery.
The furniture industry has been under self-imposed pressure to improve the fire resistance of upholstered furniture and, therefore, examined carefully the fire resistance characteristics of each component of upholstered furniture, including the welt cords. Foremost in this examination is the resistance to ignition by burning cigarettes or cigars which cause most upholstery fires.
There are two basic kinds of welt cords. One type is an extruded foam plastic bead. The fire resistance of the plastic bead was increased by enclosing a wire within and along the length of the bead to conduct heat away from a burning cigarette placed on the bead so that the plastic material near the burning cigarette will tend not to be heated to its ignition temperature. However, the welt containing the plastic bead, even though the bead is foamed, is fairly hard to the touch and, therefore, undesirable. The welt is supposed to be fairly innocuous to the touch.
Another kind of welt cord is made of cellulose filler material with a braided jacket. The cellulose welt cord has been made more fire resistant by incorporating a strip of foil into the cord along its longitudinal length to conduct heat away from a point source of heat such as a cigarette so that the cellulose near the source will not reach ignition temperature. The foil strip, however, is not resilient and has very little memory. As a result, it crimps when the cord is bent, distorting the cross-sectional shape of the bent cord at the bend. Thus, when the welt cord is bent around the cushion or couch corner, for example, the welt cord will bulge at the bend, making the welt look irregular and sloppily installed.
In one prior art cellulose construction as disclosed in U.S. patent application Ser. No. 530,416 filed on Sept. 8, 1983, entitled UPHOLSTERY WELT CORD, a small diameter foamed plastic bead was incorporated into the center of a cellulose-type welt cord with an aluminum foil layer located between the cellulose and the foam bead. When such a cord is bent the foam assists in holding the shape of the welt cord because the "memory" of the plastic core tends to restore the cord to substantially its original cross-sectional shape after bending. However, this design is not completely satisfactory in retaining the shape of the welt cord. Further, it does not eliminate another problem with the use of foils, i.e., the foil tends to break as it is being drawn into the welt cord during manufacturing. Breakage can be greatly minimized by drawing the foil slowly into the cord, but this increases production time and costs. In addition, the braiding apparatus and method is complicated by running a number of elements through the braider.